Hetisine型二萜生物碱的N——C_6键断裂新方法

Okamoto等人曾报道Hetisine型骨架的N—C_6键断裂方法,但步骤多,操作复杂。由于没有活泼基因,打断 C_6—N 键很困难,曾用Von Braun 反应,Cope 反应,Hofmann 反应均未成功。今报道改良 Hofmann 反应方法——     

我国二萜生物碱化学的最近进展

本文综述了近五年来在我国发现的61种新的二萜生物碱。     

我国二萜生物碱化学的研究进展(1986～1992)

本文综述了我国1986～1992年之间在二萜生物碱化学反应方面的研究。     

赣皖乌头生物碱的研究II. 江西兴国产赣皖乌头中其他生物碱的分离和鉴定

从江西兴国县赣皖乌头(Aconitum finetianum Hand-Mazz)根中分得五个二萜类生物碱,根据衍生物的制备、光谱分析及物理常数测定,证明其中两个为新生物碱,定名兴国乌头碱(finetianine)和1-去氢宋果灵(1-dehydrosongorine);其他三个为已知生物碱宋果灵(songorine)、诺密宁(nominine)和氨茴酰牛扁碱(anthranollycoctonine).     

藏药蓝翠雀花中的新二萜生物碱

蓝翠雀花(Delphinium caeruleum Jacq.ex Camb.)~[1]在甘肃西南部、西藏、青海等地分布较广,藏民常用其治疗牙痛、跌打损伤.其化学成分迄今未见报道.我们将其全草用乙醇浸泡,石油醚脱脂,乙醚除去色素,酸碱常法处理,氯仿萃取得总生物碱.用氧化铝、硅胶进行多次柱层析及硅胶薄层制备层析,分得碱(1)～(4).     

德钦乌头二萜生物碱成分研究

研究了乌头属植物德钦乌头(Aconitum ouvrardianum)根部二萜生物碱类化学成分。采用了柱色谱、重结晶方法进行分离纯化,根据理化性质及波谱学数据确定化合物结构。从中分离得到5个二萜生物碱,分别鉴定为黄草乌碱丁(Ⅰ)、异塔拉乌头定(Ⅱ)、塔拉萨敏(Ⅲ)、查斯曼宁(Ⅳ)和denudatine(Ⅴ)。化合物Ⅴ为首次从该植物中分离得到的C-20型二萜生物碱。     

ATISINE型二萜生物碱的圆二色谱(CD)

C_(20)-二萜生物碱结构复杂,环上大多有含氧的基团。利用NMR、MS等确定羟基、羰基在分子中的位置往往不够有力。特別是对于C_1~3或C_(11)位上羰基,没有可靠而简便的光谱鉴別方法。我们通过对几个Atisine型含羰基化合物的圆二色谱研究发现,由CD谱确定羰基在C_6位、C_(11)位及C_(13)位是一种简便有效的方法。     

一个新骨架二萜生物碱

从黄草乌(Aconitum vilmorinianum Kom.)根中分离得到一个新骨架二萜生物碱-黄乌定(vilmoridine, 1), 其骨架为B环对开海替定型, 还从该植物中分离到5个已知二萜生物碱。     

Preparation and properties of polyurethane networks based on α,ω-difunctional poly(hexafluoropropylene oxide)

Poly(hexafluoropropylene oxide), poly(HFPO), networks were prepared from functional polymers by end linking via urethane groups. The prepolymers were characterized by NMR spectroscopy and GPC. The networks were characterized by determination of the number of network chains from the shear modulus, and were snown to contain both trifunctional crosslinks and difunctional links. The properties of the networks were investigated by a range of techniques. Compared with fully-fluorinated networks formed via triazine cross-links, investigated previously, the urethane-linked networks were more readily prepared but were poorer elastomers, were less thermally stable, and were less resistant to swelling by common polar solvents. © 1995 John Wiley & Sons, Inc.     

南瓜籽烘烤前后化学成分的分析

对烘烤前后南瓜籽中的化学成分进行分析并对比。采用同时蒸馏萃取装置萃取南瓜籽中的挥发性成分,采取超临界CO2萃取技术萃取南瓜籽油脂,并将其分为酸、碱、中性三个部分,用气相色谱-质谱联用方法分析其中化学成分并进行对比。结果表明,南瓜籽挥发性成分中含有多种醛类和酯类化合物,烘烤后产生了大量的烷基吡嗪,其在碱性部分中的相对含量比烘烤前提高14倍多,不饱和醛类化合物含量也有明显提高。南瓜籽油脂中的主要化学成分是油酸、亚油酸及其酯类。还含有生物活性功能成分如植物甾醇、角鲨烯和维生素E等。烘烤后除角鲨烯含量有所降低,维生素E、植物甾醇、亚麻酸等均有提高。     

Reversed-phase high-performance liquid chromatographic, gel electrophoretic and size exclusion chromatographic studies of subunit structure of arachin and its molecular species

Arachin and its molecular species (arachin I and arachin II) were separated and isolated. The number and kind of subunits of arachin, arachin I and arachin II were determined. Studies were carried out under different experimental conditions using slab gel electrophoresis, size-exclusion chromatography and reversed-phase high-performance liquid chromatography. Gel electrophoresis was done under varying concentrations of resolving gel. Tube gel as well as slab gel electrophoresis were used and continuous as well as discontinuous buffer systems were used for both types of electrophoresis. In addition, the subunits were separated by reversed-phase HPLC using a gradient program. Arachin and arachin II were found to have 12 subunits each while arachin I showed six subunits. The subunits of arachin I were allowed to reconstitute by removing SDS. Eight combinations were tried for studying the reconstitution pattern. Molecular weight and weight ratio in each case were also determined.     

Synthesis,Luminescence and Intramolecular Energy Transfer of Binary and Ternary Rare Earth Complexes with Aromatic Carboxylic Acids and 1, 10-Phenanthroline

A series of binary and ternary rare earth complexes with para-substitued benzoic acids and 1,10-phenanthroline were synthesized. The phosphorescence spectra were measured and the lowest triplet state energies of ligands were determined, the phosphorescence lifetimes were obtained and intramolecular energy transfer mechanism between ligands was studied. The luminescence properties were also measured and were in agreement with the prediction. The energy match and intramolecular energy transfer process in these binary and ternary complexes were discussed in detail.     

IClO2异构化反应机理及电子密度拓扑研究

利用密度泛函理论方法研究了IClO2异构化反应机理. 优化得到了七种异构体, 其中OIClO和IClOO还未见报道, 对各异构体的热力学稳定性进行了比较. 找到了异构化过程的过渡态, 并通过内禀反应坐标(IRC)计算确认了各个异构体之间的相互转化关系. 从量子拓扑学的角度, 对典型异构化反应通道IRC途径上的各点进行了电子密度拓扑分析, 讨论了反应过程中化学键的断裂、生成以及化学键的变化规律, 找到了反应途径上的能量过渡态(ETS)和结构过渡态(STS).     

云南菊科中草药中铅含量特征分析

论述了云南２７种菊科中草药及其水提取物中铅含量的特征。菊科植物及水提物中铅含量的频数分布为正偏态,两者的相关系数ｒ＝０．０９,未呈现显著的线性相关。提取率较高的山紫苑、佩兰、木香铅实际含量低;铅含量高的叶下花、狭叶兔耳风、臭灵丹提取率又较低,减少了人体对Ｐｂ的过量摄入。     

PET导电纤维的制取及研究

以过氧化二苯甲酰为引发剂,使丙烯睛在涤沦(PET)纤维上接枝共聚。接枝纤维在含铜化合物,含硫还原剂溶液中反应,制备PET导电纤维。讨论了影响接枝共聚的各种因素,选择出最佳聚合条件。对该纤维的导电成份和结构以及性能进行了研究。     

Product analyses of ozone mediated nitration of benzimidazole derivatives with nitrogen dioxide: formation of 1-nitrobenzimidazoles and conversion to benzotriazoles

Several benzimidazole derivatives having electron-withdrawing or -donating substituent(s) at the benzene moiety were used as models of the imidazole moiety of purine bases and their nitration with nitrogen dioxide and ozone (so-called Kyodai nitration) were examined. Products were extracted from the reaction mixture with AcOEt and their structures were analyzed. 1-Nitrobenzimidazole derivatives and unexpected 1-nitrobenzotriazole derivatives were identified. Although the yields of 1-nitrobenzimidazole derivatives were quite low, these were all new compounds that could be obtained only by Kyodai nitration. It was speculated that benzotriazoles were formed via 1-nitrobenzimidazoles and subsequent nitration toward benzotriazoles resulted in the formation of 1-nitrobenzotriazoles.     

Analysis of endosulfan isomers and endosulfan sulfate in air and tomato leaves by gas chromatography with electron-capture detection and confirmation by gas chromatography-mass spectrometry

Rapid analytical methods for the determination of endosulfan isomers and endosulfan-sulfate in air and plant samples were developed. The insecticides were trapped from air using a column containing Florisil and extracted with a low volume of ethyl acetate, assisted by sonication. Pesticide residues were determined by gas chromatography with electron-capture detection using a nonpolar capillary column. Residue identities were confirmed by gas chromatography coupled with mass spectrometry. Recoveries of these compounds from air samples were always higher than 78% with an RSD lower than 11% and the detection limits obtained were at least 0.3 ng/l air. Leaf samples were homogenised with ethyl acetate and extracts cleaned-up on an aluminium oxide column. Pesticides were eluted with a hexane-ethyl acetate (80:20, v/v) mixture. Recoveries obtained from plant samples were higher than 78% with an RSD lower than 14% and detection limits in leaves were 0.02 microg/g for each pesticide. These methods were applied to study the volatilisation of endosulfan from tomato leaves under laboratory conditions. A volatilisation rate near 1% of the initial amount of endosulfan per hour was obtained during the first 24 h at room temperature.     

Manipulation of protein fingerprints during on-column fluorescent labeling: protein fingerprinting of six Staphylococcus species by capillary electrophoresis

Bacterial proteomes were analyzed by use of electrophoretically mediated microanalysis (EMMA) and field-enhanced stacking. A water-soluble protein fraction was injected onto a capillary. Next, a fluorogenic reagent was injected and allowed to react with the protein mixture, producing fluorescent products that were separated by submicellar capillary electrophoresis and detected by laser-induced fluorescence. By use of a low-ionic strength sample buffer and a brief electrophoretic step, slow moving anionic proteins were stacked at the reagent-sample interface and were preferentially labeled. By reversing the order of sample injection and labeling reagent, fast moving cationic proteins were preferentially labeled. By adjustment of the sample buffer pH, proteins with different isoelectric points were selectively labeled. Electrophoresis fingerprints were generated for the water-soluble protein fraction from six Staphylococcus species. The protein patterns produced were species-specific and were used to construct a phylogenetic tree.